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' 2 Sheets'Sheet 1. E. E. FISHER.

MECHANISM FOR OPERATING TELEPHONE NIGHT BELLS.

Patented Mar. 31

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(No Model.) 2 SheetsSheet 2.

P. E. FISHER. 7 MECHANISM FOR OPERATING TELEPHONE NIGHT BELLS. NO.314,817. Patented Mar. 31, 1885.

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UNITED STATES PATENT O FICE.

FRANK E. FISHER, OF DETROIT, MICHIGAN, ASSIGNOR TO THE DETROITELECTRICAL WORKS, OF SAME PLACE.

MECHANISM FOR OPERATING TELEPHONE NIGHT-BELLS.

SPECIFICATION forming part of Letters Patent No. 314,817, dated March31, 1885.

Application'filed October 1, 1884. (X model.)

Michigan, have invented a new and useful Im-' provement in Mechanism forOperating Telephone Night-Bells, of which the following is aspecification.

My invention consists in a novel arrangement of mechanism for operatingthe nightr0 bells of a telephone-exchange, and is hereinafter fullypointed out in the claims.

Figure l is a front elevation,and Fig. 2 aside elevation, of anannunciator; and Fig. 3 is a rear elevation of a section of theannunciatorboard, showing four annunciators and a nightbell, with theconnections. Fig. 4 is a longitudinal central section through Fig. 2;and Fig. 5 is an elevation of the circuit which contains the night-bell,showing a switch breaking and closing said circuit.

In telephone-exchanges it is customary during the night, when a reducedforce of'operators is in attendance, to use a call-bell with eachannunciator-board to notify the operators of a call, and this bell isdisconnected during the day, when there is an operator in attendance ateach switch-board.

A represents a section of the board which carries the annuneiators. Brepresents an' 0 electro-magnet. 0 represents a brass plate screwed tothe front of board A, to which the electro-magnetB is fastened byahollow screw, T; and G represents the drop pivoted to lugs on plate 0 atg.

3 5 The core of the electro-magnet B is hollow, and to it at one end issecured by a hollow diamagnetic screw, h, a pole-piece, D, which extendsto the circumference of the electromagnet, and to the other end issecured by a 0 diamagnetic hollow interiorly-threaded screw apole-piece, D, which extends along the outside of the eleetro-magnet,and forms a support to which the armature E is pivoted.

E represents a swinging armature pivoted 5 at e to pole-piece D, and soconstructed that one end, E, is in close proximity to polepiece D, andthe other end, F, is directly over the drop when raised, and is hookedto engage With the drop. The end F must be heavier 1 than the end E, ormust be held to the drop by alight spring. This mode of hanging thearmatureputs it in magnetic connection with one pole of the core of themagnet, so that E D really become the poles, and the magnetic attractionat that point is stronger than when 5 5 the armature is hung in anyother way.

L represents a light metal rod or needle, which passes through thehollow core of the electro-magnet B, and protrudes therefrom at bothends. One end of this needle at the right, Fig. 2, is tipped withinsulating substance 13, and the needle is prevented from touching thecore by the diamaguetic hollow screws which fasten the pole-pieces D Dand through which the needle passes. I

N 0 represent bindingposls secured to a cap of insulating materialfastened to the end of the electro-inagnet, and to them are fastened theends of the helix composing said electro-magnet.

H represents an arm of diamagnetic metal, secured to one end of the coreof the electromagnet by the screw it and insulated from said. core.

K represents a contact point formed on arm H, and extending out to orbeyond the endof screw h. r

I represents a metal spring fastened by screw m to arm H, but insulatedtherefrom, and extending far enough to press against the insulated endof needle L.

All of the arms H of the annunciators belonging to a switch-board areconnected together by wires or strips of metal, Q, and all the springs Iare similarly connected by wires or strips 1?.

R represents a battery, and S an electric 7 bell, and. one arm H isconnected with one pole of the battery. The other pole is connect edwith one binding-post of the electric bell, and the other binding-postof the bell is connected with one of the springs I, as indicated in Fig.3. So long as the arms H and springs I all remain insulated from eachother, the circuit through the battery and bell will be 5 open and thebell will not sound. If any of the springs I come in electrical contactwith the arm H which carries it,the circuit will be closed, because allthe arms H are connected, and all the springs I also connected, and thebell S will ring until the circuit is broken.

A subscribers line on entering the exchange is connected withbinding-post O, and binding-post N is connected with the switch whichbears the number shown on the annunciator, where the line is grounded inthe usual manner.

W represents an ordinary switch situated in the circuit which containsthe call-bell, whereby said circuit can be broken or closed at pleasure.I

The operation of my invention is as follows: When the drop G is turnedup and held by hooked end F of armature E, as shown in Fig. 2, the faceof the drop presses against. the end of needle L, and thus pressesspring I away from contact-point K. Vthen a subscriber sends a currentover his line to call the exchange, it passes through the helix of theelectro-magnet B and magnetizes the core thereof. Pole-piece D attractsthe end E of armature and raises the hook F, so that drop G becomesfreed therefrom, and, by its own weight, assisted by the pressure fromspring I, transmitted through needle L, the .drop falls, exposingsubscribers number. As drop G no longer presses against the end ofneedle L, this is free to move, and is moved by spring I until thespring touches contact-piece K, clos ing the circuit and ringing thebell S until the circuit is broken by raising drop G and cansing needleL to press spring I away from contact-point K.

It is obvious that for springs I may be substituted swinging pieces ofmetal so pivoted that the force of gravitation will tend to cause themto make contact with contact-points K,

except when held away therefrom by needles L, and that any such deviceis a simple mechanical equivalent for springs I.

This device entirely avoids the difficulties inherent in the mechanismnow used for similar purposes, for there is no electrical connectionbetween the night-bell mechanism and I annuciator mechanism, and nocorresponding liability to crosses or difficulty in locating crosses.

tery and bell connections.

- boards in telephoneexchanges, consisting of a metallic arm attached toeach annunciator but insulated therefrom, and all of said arms beingelectrically connected, a spring attached to but insulated from each ofsaid arms in such a manner that its free end constantly tends to makeelectrical connection with said arm, and

all of said springs being electrically connected,

mechanism, substantially such as is. described,

attached to an annunciator, the following elements, viz: anelectro-magnet having a hollow core, a pivoted armature adapted to holdor release a drop in the usual manner, a metallic arm attached to butinsulated from the electro -i'nagnet, a spring attached to but insulatedfrom the metallic arm, a needle having an insulated end extendingthrough the hollow core, and adapted to press against the drop whenraised and the free end of said spring, and a battery and electric bellin a circuit whose ends are connected, one with said arm and the otherwith said spring, substantially as shown and described.

3. In mechanism for operating a night-bell in connection with anannunciator, a battery and electric bell in a circuit having its endsconnected with two contact-pieces which are supported by but have noelectrical connection with the annunciator mechanism, a connecting-rodhaving an insulated tip resting at one end against one of saidcontact-pieces and at the other end against the drop when raised, tohold said contact-pieces apart, and a swinging drop adapted, whenraised, to hold said rod in position and release the same when it falls,substantially as shown and described.

4. The combination of the battery R and electric bell S, situated in acircuit formed in part by the fixed arm H and spring I, with the needleL, having the insulating-point t, and the pivoted drop G, substantiallyas and for the purposes described.

5. The combination, with an annunciator, of a battery and night-bell ina circuit entirely independent of the annunciator mechanism, and havingtherein two contact-pieces, one of which isfixed, while the other is aspring constantly tending to make contact with the fixed piece, and arod having an insulated end hearing against said spring-contact piece,and ex tending, when said contact-pieces are in contact, beyond theplane of a drop on the annunciator when said drop is raised, wherebyraising said drop separates said contact-pieces, and said spring-contactforces said drop to fall when released from the pawl which locks it,substantially as shown and described.

FRANK E. FISHER.

IIO

